The invention relates to transmission of area-specific information, such as weather information, on a telecommunications network, particularly on a mobile communication network.
In the GSM mobile communication system (Global System for Mobile Communication), FIG. 6, a mobile station MS is connected to a base transceiver station BTS via a radio path. A base station system BSS consists of base station controllers BSC and of base transceiver stations BTS controlled by them. A mobile services switching centre MSC usually controls several base station controllers BSC and communicates with other mobile services switching centres. The GSM network is connected to other networks, such as a public switched telephone network PSTN, another mobile communication network PLMN, an ISDN network or a service centre SC, e.g. a short message service centre SMSC, via a gateway mobile services switching centre GMSC.
One of the new services introduced into the GSM system is GPRS (General Packet Radio Service). Network elements that belong to the GPRS include SGSN (Serving GPRS Support Node), GGSN (Gateway GPRS Support Node) and PTM-SC (Point-to-Multipoint Service Centre). The SGSN maintains and updates location information of mobile stations which support the GPRS. The SGSN also contains protocol stacks for transmitting data packets to the base station system BSS and the mobile station and for receiving data packets from these. The GGSN functions as an interface to other data networks, such as the Internet or an Internet service provider. The PMT-SC transmits data packets to groups of mobile stations supporting the GPRS.
In the mobile communication system, the base transceiver stations BTS continuously transmit information on themselves and their surroundings on their broadcast channel. For example, the cell broadcast centre CBC located in the base station controller BSC manages messages of the cell broadcast channels of the base transceiver stations BTS. The cell broadcast centre transmits group transmission messages directed to each base transceiver station via the base station controller BSC according to the initial data fed in by the operator.
Group transmission of the base transceiver stations is not addressed to any particular receiver, but intended to be received by all mobile stations located in the geographic area covered by the transmission of the base transceiver station. As regards a more specific description of cell-specific group transmission, reference is made to GSM recommendation 03.41 European Digital Cellular Telecommunication System (Phase 2); Technical Realization of Short Message Service Cell Broadcast (SMSCB).
In the mobile communication system it is possible to transmit various service announcements to mobile stations. A service announcement may be e.g. a weather forecast for a certain region, which a mobile subscriber can order on the basis of his geographic location. There are, however, problems related to ordering of an area-specific announcement: it is inaccurate and slow. The area covered by one weather forecast is usually large, and thus the information ordered is inaccurate. Furthermore, the selection lists of areas are long, and thus the mobile subscriber has to go through several weather forecast areas when making his choice.
It has been suggested that the above-mentioned problems be solved by distributing area-specific information directly to the mobile stations that are in a certain area and have ordered the service. According to WO publication 98/19479 Location-Dependent Services in a Mobile Communication System, a base transceiver station transmits location information on its cell broadcast channel, a mobile station picks this location information from a group transmission and stores it. When a subscriber wants to receive a service announcement dependent on the geographic area, he initiates establishment of a short message in his mobile station, and the location information concerned is attached to the short message. A short message thus formed is transmitted to the unit that offers the service, and the unit sends the requested service announcement to the mobile station that ordered the service e.g. as a short message or as data transmission. The problem associated with this solution of the WO publication is that reception of location information and manual ordering of information cause a delay.